采用中空激光光内送粉技术,在异形基面上成形平顶薄壁结构。针对在不平整异形面上采用传统等高分层存在扫描起始端搭接缺陷、效率低等问题,提出了一种随形分层的方法:利用在一定范围内熔覆层高度与扫描速度之间、熔覆层宽度与离焦量之间的线性关系,采用分段变速以达到分段变熔高的方法使基底低点变高,从而在异形基面上逐渐堆积出平顶结构。检测结果表明:基面与层间实现了冶金结合,成形的薄壁墙顶面基本平整,最大绝对误差在0.2 mm左右,尺寸误差在8%以内;成形区域的组织致密均匀,无明显的气孔、裂纹等缺陷,显微硬度为685~720 HV。

A flat-top thin-walled structure is formed on a special-shaped base surface using hollow laser-light internal powder-feeding technology. A method of fractal stratification is proposed to solve problems of lap defects of scanning initiating terminal and low efficiency when the traditional equal-high stratification is used on uneven special surfaces. This method uses the linear relationship among the cladding height, scanning speed, cladding layer width, and defocusing amount in a certain range. A segmented variable speed is used to achieve the segmented melting height, so that the substrate low point is raised and a flat top structure is gradually added on the top of the special-shaped base surface. Test results demonstrate that, by combining the base surface and interlayer, the top surface of the thin-walled structure is typically flat. It has a maximum absolute error of approximately 0.2 mm, with a size error within 8%; the forming region's microstructure is dense and uniform without obvious pores, cracks, or other defects;the range of microhardness is 685-720 HV.